Process of treating sulphide ores of lead, silver, and copper



nted 3on2,

"er-ares Ldlllltid Earner orries,

c. ,cnrz-rsrnnsnn or s nnr nuns crrr, urnn.

success or estuarine eunrnrnn onus on teen, srtvua', nun corrna.

To all whom concern: 1 Be known thatl, Nrnns CI Cisinrs'rnnsnN, a citizen of the United States, residing at Salt Lake City, in the county of Salt v5 Lake and State of Utah, have invented cerf tain new and useful Improvements in Processes of Treating, Sulphide Ores of Lead, Silver, and Copper, oil which the following is a specification. I

This invention relates to the treatment of the sulphide ores of silver, lead and copper Either ferric chloride or ferric sulphate may be used but the former is preferablein order to avoid contamination of the solution with sulphzuves. The lerric sulphate added to the concentrated chloride solution forms ferric chloride immediately, but the sulphates build up in the solution and decrease the solubility of the metal chlorides.

l: have found that a hot solution of any of the common chlorides such as NaCl, CaCl l /lg cl or l eCl containinga small amount of ferric chloride rapidly dissolves as galena, argen ite and chalcocite. Solutions.

of KCl, Nll Cl and ll/lnCl containing terric chloride also act in the same way but would rarely be usedw Zinc chloride solution acts similarly but is much less active loowing to the more limited solubility of the silver, lead and copper chlorides in this solution. Ferric chloride alone is the least suitable of the chlorides for use as the con centrated solution or the process (as well as the active ingredient of the solution) ea, ing to thevery slight solubility of the chlorides of lead and silver in a concentrated ferric chloride solution, and a concentratedferric chloride solution is entirely unsuited to the precipitation of the free metals therefrom as the entire solution would have to be reduced to the ferrous condition before the metals (as such, not as chlorides) could be precipitated therefrom. The solutions which would be used in most cases in my process are those containing NaCl, or a. mixsilver contained in the galen Application filed octoloer S, 1919. Serial no. 329,397.

ture of NaCl and some of the following: Call-l Mgfll and .lFeCl In some places Where cheap CaCl is obtainable it might be used in preference to NaQl.

, The action of the ferric chloride, contained in the concentrated chloride solution, on the galena, argentite, and chalcocite is indicated in the following equations: 1

The lead, silver and copper are dissolved as chlorides in the hot chloride solution, "the sulphur separated as tree sulphur, and the ferric chloride is reduced to the ferrous condition. The action upon the galena is very rapid and is somewhat slower on-the' chal-. cocite and still'slower on the ar entite. The

is brought into solution just as rapidly as the galena. The time of treatment necessary to bring the metals into solution will vary with the fineness of grinding, the temperature of the so solution, the concentration of ,the ferric chloride Tin the solution, and the COBCQKIUEL-J tion of the lead, copper and silver chlorides in the-solution. Fine grinding approaching 100 mesh orliner is preferable in most cases. v The solutions act rnost' vigorously near theboiling point of the solution and hot solutions are preferable in all cases. A slight excess of ferric chloride above the amount theoretically necessary to bring the metals to into solution is desirable but a large excess is not-necessary and is not advantageous in the practical operation of the process. As the concentration of the solution in lead, silver and'copper increases the rapidity of theaction decreases and becomes extremely slow as the solution nears saturation, so that it is not advantageous toatternpt to use solutio'nstoo near saturation in regard to the lead, silver and copper. A treatment or ice from 15 to 30lrninutes with a hot solution containing asmall percentage of excess ferric chloride is sutlicient to bring the lead,

silver and copper into solution. The S given ofi during treatment may be collected without difficulty as itrises to the surface of the hot solution and may be skimmed oil. The treatment in the practical operation of the process is preferably carried out by agitating the finely ground ore or concentrate no with the hot chloride solution until the lead, silver and copper are in solution, and then decanting or filtering the hot pregnant solution away from the ore. It is advantageous to havea small amount of HCl' present in the solution to reduce the hydrolysis of the ferric chloride and prevent precipitation of ferric hydroxide. i Y

The method of precipitation. of the metals from the pregnant solution will vary with the quantity and number of metals in the orand the products desired. If the ore contains only galena, the solution may be cooled and the lead chloride separated as described in my atent application Serial Nos. 327,400 and 32%,401 or the lead'may precipitated by electrolysis as described 1n application #327,401. tains silver thisis preferably precipitated with metallic lead before the recipitatlon of the lead or lead chloride. 1 the solution contains copper as well as silver and lead the silver is'preferably first precipitated wlth metallic copper, t e copper then precipitated with metallic lead, and the lead finally precipitated by one of the methods men? tioned. The silver or copper may also be precipitated with metallic iron, as may also the lead, but the iron acts slowly upon the lead chloride in the concentrated chloride solutions, and the other methods for the precipitation of the lead are preferable. As before mentioned the exact method of precipitation will depend upon the contents of. the ore. and the products desired. My re- 4 ferred method of precipitation of the cad from solution is to electrolyze in a cell with a diaphragm between the anode and cathode compartments, the solution firstpassing into the cathode compartment where the lead is precipitated, and then into the anode cont partmentwhere the ferrous chloride is changed to ferric chloride, thus regenerating I the solution for the treatment of more ore.

If the lead is precipitated asa chloride by cooling, my preferred method of treatment is to 'electrolyze the melted lead chloride to secure lead and chlorine, and-to pass the chlorine thus generated into the ferrous chloride solution and thus regenerate the ferric chloride for the treatment of more ore.

It will be apparent,v from the foregoing that only a small excess of ferric chloride should be used as all the ferric iron must be reduced to the ferric condition before the precipitation of the gold, silver, copper or lead.

The chloride solution does not act upon pyrite or chalcopyrite, or upon some of the complex arsenical silver minerals, but does act upon zinc blende to a limited extent. lit is practically impossible, however, to secure a complete extraction of the zinc unless a very large volume of solution containing a considerable excess of ferric chloride is used. The process is therefore not Well adapted to the treatment of zinc sulphide ores for the "do not wish to be. limited llf the solution con:

the rocess, butthose ordinarily used will be Nat/l or CaCl or'a mixture of NaQl with other chlorides.

As it is obviously impossibleto describe all the variations in the details of the application of my process to all kinds ofores, l

brief description but by the appended clalms.

By my process I have secured practically complete extractions of the lead and silver from galena ores and concentrates,and have secured practically complete extractions of the lead and silver and copper from the ga-' lena and chalcocite in ores containing these minerals together with pyrite and chalcopyrite, and have left the pyrite and chalcopyby the foregoing rite in excellent condition for recovery by flotation. The silver and copper locked up in the pyrite and chalcopyrite, are recovered with these minerals. By my process l have also made practically'complete extractions of the copper in the form of chalcocite in copper concentrates and extractions of from -'98% of the silver in ores containing the silver as a sulphide. i

From the fore oing it will be apparent that my process tages over the old methods in which the ore is subjected to an oxidizing, sulphating or chloridizing roast and thereafter lixiviated for the recovery of the metals-both in the cost,-

as a great many advansimplicity of treatment and completeness of extraction.

Having described my and desire to patent is 4 1. The process of treating ores containing some of the sulphide minerals of lead, silver and copper which consists iii treating said ores wit a hot concentrated chloride solution containing ferric chloride and thereby dissolving the metals of saidminerals in said solution as chlorides, and separating said pregnant solution contaming said metal chlorides, and precipitating said metals from said pregnant solution.

2. he process of treating ores containing some of the sulphide minerals of lead, silver and copper which consistsin treating said ores with a hot concentrated chloride solution containing ferric iron in solution, and thereby dissolving the metals of said minerals in said solution as chlorides, and separating said pregnant solution containing said metal chlorides, and precipitating said metals from said pregnant solution.

3. The process of treating ores containing some of the sulphide minerals of lead, silver and copper which consists in treating said process what ll claim menace ores with a hot concentrated chloride solution containing ferric chloride and thereby dissolving the metals of said minerals in said solution as chlorides, and separating said' pregnant solution containing said metal chlorides, and precipitating the silver with metallic copper, the copper with metallic lead, and the lead by electrolysis from said solution.

4. The process of treating ores containing some of the su] hide minerals of lead, silver and cop-per which consists in treating said ores with a hot concentrated chloride solution containing ferric chloride, and thereby dissolving the metals of said minerals as chlorides, and freeing the metallic sulphur, and, reducing the ferric chloride-to the ferrous condition; separating said pregnant solution containing said chlorides from the remainder of'the ore, and precipitating the;

metals therefrom by electrolysis, and using,

the chlorine generated in said electrolysis to convert ferrous chloride formed by above said treatment to the ferric condition, and using the ferric solution thus formed for the treatment of more ore.

5. The process of treating ores containing some of the sulphide minerals of lead, silver and copper, which consists intreating said ores with a hot concentrated-chloride solution containing ferric chloride ,and thereby dissolving the metals of said minerals in said solution as chlorides, and separating said pregnant solution containing said metal chlorides from the residue' of ore and precipitating the silver with metallic copper,

NIELS C. CHRISTENSEN. 

